Impact of iodine status during pregnancy on maternal and neonatal thyroid function and birth weight outcome: a systematic review

Abstract

Abstract Background: Iodine status plays a crucial role throughout the course of pregnancy as some major changes in thyroid function are found to be occurred during pregnancy because of hormonal changes and metabolic requirements during pregnancy. In case of iodine deficiency, production of maternal thyroid hormones may be deceased which may cause adverse effect on the thyroid functions of the pregnant mothers as well as their neonatal. Objective: This study aims to explore the impact of iodine status on maternal thyroid hormonal function and its effect on birth weight outcomes for infants in time of birth Methods: In this study, a comprehensive systematic literature review was conducted and in doing so an electronic database searching was performed using different electronic databases such as PubMed, MEDLINE, BMJ, and Cochrane library database to include cohort studies, cross-sectional studies and randomised controlled trials published after 2010 and which were available in English Language. For each of the study, data were extracted in terms of their study design, participants’ characteristics, intervention type, outcome measured, and key findings of the study in terms of maternal thyroid function and neonatal birth weight. Results: From the literature searching and using the inclusion and exclusion criteria, a total nine studies were included among which four studies were population-based prospective cohort studies, followed by two cross-sectional studies, two randomised controlled trial and one prospective randomised intervention based study. From the systematic review it is found that iodine status during pregnancy significantly associated with the concentration of serum thyroid hormones in the pregnant mother and affects the maternal thyroid function. However, no significant association is found about the impact of iodine status during pregnancy on the birth weight of the neonatal, though few studies have shown association between iodine status and neonatal thyroid function. Conclusion: Iodine status during pregnancy is significantly associated with maternal thyroid hormones and thyroid functions and therefore, pregnant women should be provided with adequate iodine intake throughout their pregnancy in order to avoid severe health outcomes for both the mother and their infants.